The description of the relation between the moonlight and the conception has been long discussed, having its origin in the approximate coincidence of the lunar revolution period (29 days) and the ovulation regular cycles, that oscillate around that figure.

The moon has 4 cycles: Full moon, First quarter, New Moon, Last quarter.

Nowadays, it is believed that pregnant women start their delivery under the influence of full moon.

The aims of the study were: o To determine if there is an increase in the number of deliveries in the delivery room of the University Hospital Virgen de la Arrixaca depending on the moon cycle.

o To determine if there is an increase of the deliveries in a specific cycle of the moon.

An observational, retrospective and descriptive study was carried out. A total of 5,421 labors were studied during the 10 lunar cycles (from January 10th, 2005 to November 1st, 2005). The results were during new moon: 1,372 labors (25,31%), during first quarter 1,323 labors (24,41%), during full moon: 1,348 labors (24,87%), and during last quarter: 1,378 labors (25,42%).

Conclusion: o We have not found significant evidences on the relation between any moon cycles and an increase of the deliveries.

o After breaking each cycle down into the number of labors according to the beginning, we can also conclude that there was not an important increase in the induction in none of the several lunar cycles.